There is no way to stop the wear, except to not wear the boots. But you can get a good shoe repair shop to put a patch on. But toe wear? That indicates that either you are dragging your feet {;>D or using the boots for rock climbing. Check how you are walking and maybe pick your feet up, or maybe get rock climbing shoes.

More seriously, the rand on the Sundowners should protect the leather in normal hiking. If you go to a shoe shop that does a lot of boot repairs, discuss the wear with them. There are some good boot repair shops that advertise in the backcountry magazines. There is a good one in Bishop, CA that deals with PCT and JMT hikers, and IIRC, several at access points along the AT as well. I recall from when I lived in New England and from a recent visit there that there is a shop in North Conway, NH that works with hikers, plus in Boulder, CO, Gary Neptune (Neptune Mountaineering, not far from CU campus) can refer you to a local bootmaker.